JPH05185807A - Pneumatic radial tire - Google Patents
Pneumatic radial tireInfo
- Publication number
- JPH05185807A JPH05185807A JP4176269A JP17626992A JPH05185807A JP H05185807 A JPH05185807 A JP H05185807A JP 4176269 A JP4176269 A JP 4176269A JP 17626992 A JP17626992 A JP 17626992A JP H05185807 A JPH05185807 A JP H05185807A
- Authority
- JP
- Japan
- Prior art keywords
- tire
- tread
- curvature
- radius
- belt
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Granted
Links
Classifications
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B60—VEHICLES IN GENERAL
- B60C—VEHICLE TYRES; TYRE INFLATION; TYRE CHANGING; CONNECTING VALVES TO INFLATABLE ELASTIC BODIES IN GENERAL; DEVICES OR ARRANGEMENTS RELATED TO TYRES
- B60C11/00—Tyre tread bands; Tread patterns; Anti-skid inserts
- B60C11/0083—Tyre tread bands; Tread patterns; Anti-skid inserts characterised by the curvature of the tyre tread
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B60—VEHICLES IN GENERAL
- B60C—VEHICLE TYRES; TYRE INFLATION; TYRE CHANGING; CONNECTING VALVES TO INFLATABLE ELASTIC BODIES IN GENERAL; DEVICES OR ARRANGEMENTS RELATED TO TYRES
- B60C11/00—Tyre tread bands; Tread patterns; Anti-skid inserts
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B60—VEHICLES IN GENERAL
- B60C—VEHICLE TYRES; TYRE INFLATION; TYRE CHANGING; CONNECTING VALVES TO INFLATABLE ELASTIC BODIES IN GENERAL; DEVICES OR ARRANGEMENTS RELATED TO TYRES
- B60C3/00—Tyres characterised by the transverse section
- B60C3/04—Tyres characterised by the transverse section characterised by the relative dimensions of the section, e.g. low profile
Landscapes
- Engineering & Computer Science (AREA)
- Mechanical Engineering (AREA)
- Tires In General (AREA)
Abstract
Description
【０００１】[0001]
【産業上の利用分野】本発明はトレッド部の耐バックリ
ング性を高めることによって、トレッド部の耐久性を向
上しうる空気入りラジアルタイヤに関する。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pneumatic radial tire which can improve the durability of the tread portion by improving the buckling resistance of the tread portion.
【０００２】[0002]
【従来の技術】小型トラック、等の小型貨物車用のタイ
ヤおよび、ジープ等泥濘地、砂地等オフロードの走行を
目的とする四輪駆動車用のタイヤにあっては、走行の安
定性と乗心地とを保持するため低内圧で使用されること
が多い。一方このような小型貨物車用のタイヤにあって
は、使用荷重の増大とともに偏平化の傾向にある。又泥
濘地、砂地を走行する四輪駆動車にあっては、フローテ
ィング性能を高めるため偏平化に進みつつある。2. Description of the Prior Art Tires for small freight vehicles such as small trucks and tires for four-wheel drive vehicles intended for off-road traveling such as jeep and mud, sandy land, etc. It is often used at low internal pressure to maintain riding comfort. On the other hand, such a small freight vehicle tire tends to be flattened as the working load increases. In addition, four-wheel drive vehicles that run on mud and sand are becoming flatter in order to improve their floating performance.
【０００３】[0003]
【発明が解決しようとする課題】しかし偏平化すること
により接地面が増大する結果、接地圧を減じる一方、走
行時においてベルト層がタイヤ半径方向に繰返し曲げ変
形を受けることにより、ベルト層の端部、又は溝底近傍
において周方向に破断するいわゆるバックリングが多々
生じる結果となった。However, the flattening of the ground contact surface due to the flattening reduces the ground contact pressure, while the belt layer is repeatedly subjected to bending deformation in the tire radial direction during running, so that the end of the belt layer is reduced. As a result, so-called buckling, which fractures in the circumferential direction, often occurs in the portion or near the groove bottom.
【０００４】通常、小型トラック用及び四輪駆動車用の
タイヤにあっては、ベルト層の変形を少なくするため、
トレッド部はその中央部をトレッドショルダ部に比べて
厚肉に形成され、従ってジープ用などの高荷重を受ける
タイヤにあっては、中央部におけるゴム厚さが異常に大
きくなる結果、タイヤ重量が増しコストも増大すること
となる。Usually, in tires for small trucks and four-wheel drive vehicles, in order to reduce deformation of the belt layer,
The tread portion is formed thicker in the central portion than the tread shoulder portion.Therefore, in a tire that receives a high load such as a jeep, as a result of the rubber thickness in the central portion becoming abnormally large, the tire weight is increased. The cost will also increase.
【０００５】従ってトレッド部のゴムを異状な厚肉にす
ることなくベルト層を破損から保護できるタイヤの構成
が必要となった。Therefore, there is a need for a tire structure capable of protecting the belt layer from damage without making the rubber of the tread portion into an abnormally thick wall.
【０００６】発明者は前記問題点を解決すべく鋭意研究
の結果、従来、配慮されることがなかったトレッド表面
の曲率半径とベルト層の曲率半径との間に互いに関連性
について着目し、本発明を完成させたのである。As a result of earnest research aimed at solving the above-mentioned problems, the inventor paid attention to the mutual relationship between the radius of curvature of the tread surface and the radius of curvature of the belt layer, which has not been taken into consideration in the past. The invention was completed.
【０００７】本発明は、トレッド表面の曲率半径とベル
ト層の曲率半径との相対関係を規制することによりベル
ト層のバックリングに起因する破損を防ぐことによっ
て、タイヤの耐久性を向上しうる空気入りラジアルタイ
ヤの提供を目的としている。According to the present invention, by controlling the relative relationship between the radius of curvature of the tread surface and the radius of curvature of the belt layer, damages caused by buckling of the belt layer can be prevented, thereby improving the durability of the tire. The purpose is to provide radial tires with the inside.
【０００８】[0008]
【課題を解決するための手段】本発明は、タイヤ最大巾
とタイヤ最大径との和が７５０mm以上かつ１２５０mm以
下、しかもトレッド部からサイドウォール部を通りビー
ド部のビードコアの周りを折返すカーカスと、トレッド
部の内部かつカーカスの半径方向外側に配されかつ１枚
以上のベルトプライからなるベルト層とを具える空気入
りラジアルタイヤであって、タイヤ子午断面におけるト
レッド部表面と、前記ベルト層の半径方向外側のベルト
層の外面とはともにタイヤ赤道面を中心とする円弧によ
って形成されるとともに、トレッド部表面の曲率半径で
あるトレッド曲率半径（ＴＲ１）はベルト層外面の曲率
半径であるベルト曲率半径（ＢＲ１）よりも大、しかも
前記トレッド曲率半径（ＴＲ１）とベルト曲率半径（Ｂ
Ｒ１）との積（ＴＲ１×ＢＲ１）は３３．７×１０4 m
m2以上かつ４５．０×１０4 mm2以下であることを特徴
とする空気入りラジアルタイヤである。SUMMARY OF THE INVENTION The present invention provides a carcass having a tire maximum width and a tire maximum diameter of 750 mm or more and 1250 mm or less, and folding back around the bead core of the bead portion through the tread portion and the sidewall portion. A pneumatic radial tire provided inside the tread portion and outside in the radial direction of the carcass and comprising a belt layer composed of one or more belt plies, the tread portion surface in a tire meridional section, and the belt layer The outer surface of the belt layer on the outer side in the radial direction is formed by an arc centered on the tire equatorial plane, and the tread curvature radius (TR1), which is the radius of curvature of the surface of the tread portion, is the radius of curvature of the outer surface of the belt layer. Larger than the radius (BR1), and the radius of curvature of the tread (TR1) and the radius of curvature of the belt (B
R1) product (TR1 × BR1) is 33.7 × 10 4 m
A pneumatic radial tire characterized by having a size of not less than m 2 and not more than 45.0 × 10 4 mm 2 .
【０００９】[0009]
【作用】トレッド曲率半径ＴＲ１をベルト曲率半径ＢＲ
１よりも大きくしている。従ってトレッド部のゴム厚さ
は、その中央部がトレッド部端縁近傍のトレッドショル
ダ部のゴム厚さよりも大となる。その結果、トレッド曲
率半径ＴＲ１を図２（Ａ）に示す如くベルト曲率半径Ｂ
Ｒ１よりも大とすることによって、着地時即ち負荷時に
は、図２（Ｂ）に示すようにトレッド表面は平坦かつベ
ルト層は中央部が半径方向外方に膨らむ凸湾曲状とな
る。[Operation] Tread curvature radius TR1 is set to belt curvature radius BR
It is larger than 1. Therefore, the rubber thickness of the tread portion is larger than the rubber thickness of the tread shoulder portion near the end edge of the tread portion at the center thereof. As a result, the tread curvature radius TR1 is set to the belt curvature radius B as shown in FIG.
When it is set to be larger than R1, at the time of landing, that is, at the time of loading, the tread surface is flat and the belt layer has a convex curved shape in which the central portion bulges outward in the radial direction, as shown in FIG. 2B.
【００１０】他方トレッド部曲率半径ｔｒ１がベルト曲
率ｂｒ１に比べて小とした場合には、無負荷時における
図３（Ａ）の状態から荷重が加わることによるトレッド
部表面の平坦化とともにベルト層ｂは、図３（Ｂ）に示
す如く中央部が半径方向内方に凹む凹状に変形する。し
かもこの変形はタイヤの走行時において、着地時、非着
地時ごとに無負荷状態と、負荷状態とが反復して作用す
ることとなり、前記ベルト層ｂは凸湾曲と凹湾曲とを繰
返すこととなる。その結果、ベルト層ｂを形成するベル
トコードには、引張りと圧縮とが繰返し作用し、ベルト
層ｂの端部の剥離、さらにはベルトコード自体の疲労破
壊による切断によって、いわゆるバックリング性能の低
下により耐久性を著しく低下させることとなる。この傾
向は、ベルトコードを剛性の高い材料、例えばスチール
等で形成した場合には特に著しい。On the other hand, when the radius of curvature tr1 of the tread portion is made smaller than the curvature of the belt br1, the surface of the tread portion is flattened by applying a load from the state of FIG. As shown in FIG. 3B, the central portion is deformed into a concave shape that is concave inward in the radial direction. In addition, this deformation means that the tire is in a non-loaded state and a loaded state is repeatedly acted upon each of landing and non-landing when the tire is running, and the belt layer b repeats a convex curve and a concave curve. Become. As a result, the belt cord forming the belt layer b is repeatedly subjected to tension and compression, and the so-called buckling performance is deteriorated due to the peeling of the end portion of the belt layer b and the cutting due to the fatigue fracture of the belt cord itself. As a result, the durability is significantly reduced. This tendency is particularly remarkable when the belt cord is made of a highly rigid material such as steel.
【００１１】ここでバックリング性能とは、走行するこ
とによってベルト層が繰返し歪又は挫屈を受け、溝底近
傍又はベルト層端湾曲等でタイヤ周方向に切断すること
を言い、又バックリング性の評価方法としては、図４に
示す如くリム組みされたタイヤｔを負荷状態に保持する
とともに、該タイヤｔにタイヤ軸方向に横力ｆを加える
ことによって生じるベルト層ｂの浮上がり量を測定す
る。The term "buckling performance" as used herein means that the belt layer is repeatedly distorted or buckled by running and is cut in the tire circumferential direction near the groove bottom or at the belt layer edge curve, and also has a buckling property. As a method for evaluating, the tire t assembled to the rim as shown in FIG. 4 is maintained in a loaded state, and the amount of lift of the belt layer b generated by applying a lateral force f to the tire t in the tire axial direction is measured. To do.
【００１２】なお前記ベルト層ｂの浮上がり量を測定す
る方法としては、例えばトレッドゴムをタイヤ軸方向に
接地長さ以上、かつ周方向に１０mm除去することにより
ベルト層を露出させた試供タイヤｔを接地させるととも
に、該タイヤｔに横力ｆを加える。この際横力ｆが加わ
る前後における接地面ｌとベルト層ｂとの距離ｙ１及び
ｙ２についてそれぞれ石膏を用いて測定するとともに横
力ｆを付加した時の距離ｙ２から付加前の距離ｙ１を差
引いた値をもってバックリング量Ｙと規定している。As a method for measuring the amount of lifting of the belt layer b, a test tire t in which the belt layer is exposed by removing tread rubber for at least the ground contact length in the tire axial direction and for 10 mm in the circumferential direction is used. Is grounded and a lateral force f is applied to the tire t. At this time, the distances y1 and y2 between the grounding surface 1 and the belt layer b before and after the lateral force f was applied were measured using gypsum respectively, and the distance y1 before the lateral force f was subtracted from the distance y1 before the lateral force f was applied. The value is defined as the buckling amount Y.
【００１３】そこでタイヤサイズが３１×１０．５Ｒ１
５でありかつトレッド曲率半径ＴＲ１をベルト曲率半径
ＢＲ１よりも大とした複数本のタイヤを試作するととも
に該タイヤを７ＪＴ×１５のリムに装着し、内圧２．０
kgｆ／cm2 、荷重０．９８０kgｆのもとで前記バックリ
ング量Ｙを測定するとともに、トレッド曲率半径とベル
ト曲率半径との積（ＴＲ１×ＢＲ１）とそのバックリン
グ量Ｙとの相関について調査した。調査結果を図５のグ
ラフに◇印をもって示す。グラフから理解できるように
両半径の積（Ｘ＝ＴＲ１×ＢＲ１）とバックリング量Ｙ
との間には、Ｙ＝１０．３７２−０．２４８１×１０-4
Ｘ（相関係数０．９８８）なる直線Ｌからなる関係が得
られる。Therefore, the tire size is 31 × 10.5R1.
A plurality of tires having a tread radius of curvature TR1 larger than the belt radius of curvature BR1 were prototyped, and the tires were mounted on a rim of 7 JT × 15, and the internal pressure was 2.0.
The buckling amount Y was measured under kgf / cm 2 and a load of 0.980 kgf, and the correlation between the product (TR1 × BR1) of the tread curvature radius and the belt curvature radius and the buckling amount Y was investigated. .. The survey results are shown in the graph of Fig. 5 with a ◇ mark. As can be understood from the graph, the product of both radii (X = TR1 × BR1) and the buckling amount Y
And Y = 10.372-0.2481 × 10 -4
A relationship composed of a straight line L of X (correlation coefficient 0.988) is obtained.
【００１４】しかし、トレッド曲率半径ＴＲ１及びベル
ト曲率半径ＢＲ１をともに小とした場合であってもバッ
クリング量Ｙの規則値を満たし得るのであるが、トレッ
ド曲率半径ＴＲ１が小となることにより、トレッド部の
接地面積が減じ接地圧が大となる結果、トレッド部の耐
摩耗性が低下する。又トレッド部は接地により局部的に
変形することによって、ベルト層及びトレッドゴムに局
部的な変形が生じ、その変形によってトレッド部は破損
する危険がある。However, even if both the tread radius of curvature TR1 and the belt radius of curvature BR1 are small, the regular value of the buckling amount Y can be satisfied. However, since the tread radius of curvature TR1 becomes small, the tread is reduced. As a result of the ground contact area of the portion being reduced and the ground contact pressure being increased, the wear resistance of the tread portion is reduced. Further, the tread portion is locally deformed by grounding, so that the belt layer and the tread rubber are locally deformed, and there is a risk that the tread portion is damaged by the deformation.
【００１５】従って、トレッド曲率半径ＴＲ１、ベルト
曲率半径ＢＲ１をともに大、即ち平坦に近づけるのが耐
摩耗性に対して良好であり、又バックリング量Ｙは、
２．００mm以下ならばベルト層の破損は生じるおそれは
ない。その結果、バックリング量Ｙの前記２．００mmラ
インＨと前記直線Ｌとの交点Ｐである両半径の積（ＴＲ
１×ＢＲ１）の値を３３．７×１０4 mm2以上に規制し
たのである。Therefore, it is good for the wear resistance to make both the tread curvature radius TR1 and the belt curvature radius BR1 large, that is, close to flat, and the buckling amount Y is
If it is 2.00 mm or less, there is no possibility that the belt layer will be damaged. As a result, the product of both radii (TR) at the intersection point P of the 2.00 mm line H of the buckling amount Y and the straight line L (TR
The value of 1 × BR1) was regulated to 33.7 × 10 4 mm 2 or more.
【００１６】又前記両半径の積（ＴＲ１×ＢＲ１）の値
を３３．７×１０4 mm2 以上とすることによって、泥濘
地、砂地走行に対してフローティング効果が高まり、軟
弱地における走行能力が高まる。By setting the value of the product of both radii (TR1 × BR1) to 33.7 × 10 4 mm 2 or more, the floating effect is enhanced for running on mud and sand, and running ability on soft ground is improved. Increase.
【００１７】他方トレッド曲率半径ＴＲ１とベルト曲率
半径ＢＲ１との積（ＴＲ１×ＢＲ１）が４５．０×１０
4 mm2をこえると前記接地面がタイヤ軸方向に過大に拡
がるため、特にオンロード走行時において直進安定性、
旋回性などの操縦安定性が低下する。On the other hand, the product (TR1 × BR1) of the tread curvature radius TR1 and the belt curvature radius BR1 is 45.0 × 10.
If it exceeds 4 mm 2 , the contact surface spreads excessively in the axial direction of the tire, so stability in straight running, especially when traveling on road,
Maneuvering stability such as turning performance is reduced.
【００１８】[0018]
【実施例】以下本発明の一実施例を図面に基づき説明す
る。図において空気入りラジアルタイヤ１は、タイヤ最
大巾Ｗとタイヤ最大径との和が７５０mm以上かつ１２５
０mm以下である。従って低内圧かつ高荷重で使用される
タイヤサイズとして３１×１０．５０Ｒ１５、３２×１
２．５０Ｒ１５などの小型トラック及び四輪駆動車用の
タイヤは含まれる。又空気入りラジアルタイヤ１はトレ
ッド表面２Ａを形成するトレッド部２からサイドウォー
ル部３をへてビード部４のビードコア５の周りを折返す
カーカス６とトレッド部２の内部かつカーカス６の外側
に配されるベルト層７を具える。DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. In the figure, the pneumatic radial tire 1 has a maximum tire width W and a maximum tire diameter of 750 mm or more and 125 or more.
It is 0 mm or less. Therefore, the tire size used at low internal pressure and high load is 31 × 10.50R15, 32 × 1
Tires for light trucks and four-wheel drive vehicles such as the 2.50R15 are included. Further, the pneumatic radial tire 1 is disposed inside the tread portion 2 and the carcass 6 that is folded back around the bead core 5 of the bead portion 4 from the tread portion 2 forming the tread surface 2A to the sidewall portion 3 and outside the carcass 6. The belt layer 7 is provided.
【００１９】カーカス６は、例えばナイロン、レーヨ
ン、ポリエステル、芳香族ポリアミド繊維などの有機繊
維又はスチールからなるカーカスコードをタイヤ赤道Ｃ
に対して本例では７０〜９０°の角度で傾けて配列した
ラジアル又はセミラジアル配列のカーカスプライを単数
又は複数枚、本例では１枚により形成される。The carcass 6 is, for example, a carcass cord made of steel such as nylon, rayon, polyester, aromatic polyamide fiber or steel, or a tire equator C.
On the other hand, in this example, one or a plurality of radial or semi-radially arranged carcass plies are arranged at an angle of 70 to 90 °, and in this example, one carcass ply is formed.
【００２０】ベルト層７は単数又は複数枚、本例では２
枚のベルトプライ７Ａ、７Ａからなり、各ベルトプライ
７Ａはカーカスプライと同様にナイロン、レーヨン、ポ
リエステル、芳香族ポリアミド繊維などの有機繊維又は
スチールからなるベルトコードを互いに交差する向きに
配している。The number of belt layers 7 is one or plural, and in this example, 2
Like the carcass ply, each belt ply 7A is composed of a number of belt plies 7A and 7A, and belt cords made of steel or organic fiber such as nylon, rayon, polyester, aromatic polyamide fiber or steel are arranged in a direction intersecting with each other. ..
【００２１】トレッド部表面２Ａはタイヤ赤道Ｃ面を中
心とし一定の曲率半径ＴＲ１を有する単一の円弧からな
り、又前記ベルト層７の半径方向外側の外面、即ち最外
側に位置するベルトプライ７Ａの外向き面もまたタイヤ
赤道Ｃ面を中心とし一定の曲率は半径ＢＲ１を有する単
一の円弧によって形成される。The tread surface 2A is composed of a single circular arc having a constant radius of curvature TR1 with the tire equatorial plane C as the center, and the outer surface of the belt layer 7 in the radial direction, that is, the outermost belt ply 7A. The outward-facing surface is also centered on the tire equatorial plane C and has a constant curvature formed by a single arc having a radius BR1.
【００２２】本実施例ではトレッド部表面の曲率半径で
あるトレッド曲率半径ＴＲ１を４００mmよりも大かつ１
０００よりも小の範囲としている。トレッド曲率半径Ｔ
Ｒ１が４００mm以下となればタイヤに荷重が負荷された
時と無負荷時とにおいてベルト層のズレが大となる結
果、耐久性に劣る一方、１０００mm以上となれば荒れ地
などの不整地を走行する際に走破性能が低下するからで
ある。In this embodiment, the tread radius of curvature TR1 which is the radius of curvature of the tread surface is larger than 400 mm and 1
The range is smaller than 000. Tread radius of curvature T
If R1 is 400 mm or less, the deviation of the belt layer becomes large when the tire is loaded and when the tire is not loaded, resulting in poor durability. On the other hand, when R1 is 1000 mm or more, the tire runs on rough terrain. This is because the running performance will decrease.
【００２３】ベルト層７は、本実施例ではそのタイヤ軸
方向の長さであるベルト巾ＢＷを前記タイヤ最大巾Ｗの
０．６倍よりも大かつ０．８５よりも小としている。
０．６倍以下ではトレッド部の横剛性が低下する一方、
０．８５以上では、ころがり抵抗が減じ操縦安定性が向
上するのであるが偏摩耗が生じるなど耐久性が低下し好
ましくない。In this embodiment, the belt layer 7 has a belt width BW, which is a length in the tire axial direction, larger than 0.6 times the tire maximum width W and smaller than 0.85.
If it is less than 0.6 times, the lateral rigidity of the tread portion will decrease,
When it is 0.85 or more, rolling resistance is reduced and steering stability is improved, but durability is reduced such as uneven wear, which is not preferable.
【００２４】又、ベルト層７の外面の曲率半径であるベ
ルト曲率半径ＢＲ１は前記トレッド曲率半径ＴＲ１より
も小としている。従ってトレッド部２にあっては、ベル
ト層７の外側かつトレッド部表面２Ａとの間のゴムはト
レッド部２の中央部Ｃｒのゴム厚さがトレッドショルダ
部Ｓｈのゴム厚さに比べて薄肉に形成される。The belt radius of curvature BR1 which is the radius of curvature of the outer surface of the belt layer 7 is smaller than the tread radius of curvature TR1. Therefore, in the tread portion 2, the rubber between the outer side of the belt layer 7 and the surface 2A of the tread portion has a rubber thickness of the central portion Cr of the tread portion 2 which is smaller than that of the tread shoulder portion Sh. It is formed.
【００２５】ベルト曲率半径ＢＲ１がトレッド曲率半径
ＴＲ１よりも大となれば負荷時において図３（Ｂ）に示
すようにベルト層が逆反りとなり、バックリングが生じ
やすい。なおベルト曲率半径ＢＲ１が３９５mm以下では
操縦安定性が低下するおそれがある。If the belt radius of curvature BR1 is larger than the tread radius of curvature TR1, the belt layer is reversely warped as shown in FIG. 3 (B) when loaded, and buckling is likely to occur. If the belt curvature radius BR1 is 395 mm or less, steering stability may be reduced.
【００２６】又前記トレッド曲率半径ＴＲ１とベルト曲
率半径ＢＲ１とは、両曲率半径の積（ＴＲ１×ＢＲ１）
を３３．７×１０4 mm2以上かつ４５．０×１０4 mm2
以下の範囲に設定している。このような両曲率半径の積
（ＴＲ１×ＢＲ１）の値の上限値、下限値をそれぞれ規
制することによってタイヤの走行諸性能を損なうことな
く、耐バックリング性をも高め、ベルト層７を破壊から
保護し耐久性を高めうるのである。The tread radius of curvature TR1 and the belt radius of curvature BR1 are the product of the two radii of curvature (TR1 × BR1).
33.7 × 10 4 mm 2 or more and 45.0 × 10 4 mm 2
It is set to the following range. By restricting the upper limit value and the lower limit value of the product of both radii of curvature (TR1 × BR1), the buckling resistance is enhanced and the belt layer 7 is destroyed without impairing the running performance of the tire. It is possible to improve the durability by protecting from.
【００２７】なお泥濘地、砂地走行を目的とする四輪駆
動車のタイヤにあっても本発明に係る構成による空気入
りラジアルタイヤを採用することが出来る。泥濘地、砂
地を走行するため、トレッド部は、例えば図６に示すよ
うに、オンロード走行を目的とする一般的なタイヤに比
べて、荷重に対する内圧が比較的低い内圧のもとで使用
され、しかも前記一般的なタイヤに比べて曲げ剛性をよ
り小さく設定している。さらに四輪駆動車用のタイヤに
あっては、トレッド面には周方向溝及びこの周方向溝と
交わる向きに配される横溝とによってトレッド面２に複
数のブロックを配したブロックパターンが形成されてい
るのである。The pneumatic radial tire having the structure according to the present invention can be adopted even for a tire of a four-wheel drive vehicle for traveling on mud and sand. Since it runs on mud and sand, the tread is used under an internal pressure that is relatively low compared to a general tire for on-road running, as shown in FIG. 6, for example. Moreover, the bending rigidity is set smaller than that of the general tire. Further, in a tire for a four-wheel drive vehicle, a block pattern in which a plurality of blocks are arranged on the tread surface 2 is formed on the tread surface by a circumferential groove and lateral grooves arranged in a direction intersecting with the circumferential groove. -ing
【００２８】このような低内圧かつ高荷重のもとで使用
され、しかも泥濘地、砂地を走行するためタイヤ容積に
比してタイヤ基体の各部分の厚さが薄く形成された四輪
駆動車用タイヤにあっては、トレッド部の断面厚さ及び
トレッドパターンにおける溝部と陸部との比であるシー
・ランド比を規制するのが好ましい。A four-wheel drive vehicle which is used under such a low internal pressure and a high load, and further, because it travels on mud and sand, the thickness of each part of the tire base is smaller than the tire volume. In a tire for use in a vehicle, it is preferable to regulate the cross-sectional thickness of the tread portion and the sea-land ratio, which is the ratio of the groove portion to the land portion in the tread pattern.
【００２９】本実施例ではタイヤ赤道Ｃにおけるトレッ
ド部２の全厚さＴ１とタイヤ最大巾Ｗとの比である厚さ
比Ｔ１／Ｗを０．０５よりも大かつ０．０７３よりも小
としている。前記比が０．０５以下では摩耗代が少なく
耐摩耗性が劣る一方０．０７３以上ではトレッド部の曲
げ剛性が大となり泥濘地、砂地を走行する際にフローテ
ィング効果に劣ることとなる。In this embodiment, the thickness ratio T1 / W, which is the ratio of the total thickness T1 of the tread portion 2 at the tire equator C to the maximum tire width W, is set to be larger than 0.05 and smaller than 0.073. There is. If the ratio is 0.05 or less, the wear margin is small and the wear resistance is poor. On the other hand, if the ratio is 0.073 or more, the bending rigidity of the tread portion is large and the floating effect is poor when traveling on mud or sand.
【００３０】又前記フローテング効果を高めるには陸面
積の総和／溝面積の総和である前記シー・ランド比が４
０／６０以上であることが好ましい。In order to enhance the floating effect, the sea-land ratio, which is the sum of land area / groove area, is 4
It is preferably 0/60 or more.
【００３１】[0031]
【具体例】タイヤサイズが３１×１０．５０ Ｒ１５で
ありかつ図１に示す構成を有するタイヤ（実施例１〜
２）について表１に示す仕様にて試作するとともにバッ
クリング量Ｙについて測定した。又本願構成以外のタイ
ヤについても併せて試作しその性能を比較した。なおバ
ックリング量Ｙの測定については、（作用）項で述べた
測定方法に準據して行った。テストの結果、実施例のも
のは比較例のものに比べてバックリング量Ｙを著減し得
たことが確認できた。SPECIFIC EXAMPLE A tire having a tire size of 31 × 10.50 R15 and having the structure shown in FIG. 1 (Examples 1 to 1)
Regarding 2), a prototype was produced according to the specifications shown in Table 1, and the buckling amount Y was measured. Further, tires other than the structure of the present application were also prototyped and their performances were compared. The buckling amount Y was measured according to the measuring method described in the section (action). As a result of the test, it was confirmed that the buckling amount Y of the example could be significantly reduced as compared with the comparative example.
【００３２】[0032]
【発明の効果】叙上の如く本発明の空気入りラジアルタ
イヤは、トレッド曲率半径をベルト曲率半径よりも大、
かつトレッド曲率半径とベルト曲率半径との積を規制し
たため、トレッド部の耐バックリング性を高めトレッド
部の耐久性を向上することが出来る。As described above, in the pneumatic radial tire of the present invention, the tread radius of curvature is larger than the belt radius of curvature,
Moreover, since the product of the radius of curvature of the tread and the radius of curvature of the belt is regulated, it is possible to enhance the backing resistance of the tread portion and improve the durability of the tread portion.
【図１】本発明の一実施例を示す断面図である。FIG. 1 is a sectional view showing an embodiment of the present invention.
【図２】作用を示す断面図であり、（Ａ）は非接地時、
（Ｂ）は接地時の状態をそれぞれ示す。FIG. 2 is a cross-sectional view showing an operation, (A) is a non-grounded state,
(B) shows the state at the time of grounding.
【図３】従来のタイヤの作用を示す断面図であり、
（Ａ）は非接地時、（Ｂ）は接地時の状態をそれぞれ示
す。FIG. 3 is a cross-sectional view showing the operation of a conventional tire,
(A) shows a state when not grounded, and (B) shows a state when grounded.
【図４】バックリング量の測定方法を示す正面図であ
る。FIG. 4 is a front view showing a method of measuring the amount of buckling.
【図５】トレッド曲率半径とベルト曲率半径との積に対
するバックリング量の関係を示すグラフである。FIG. 5 is a graph showing a relationship between a buckling amount and a product of a radius of curvature of a tread and a radius of curvature of a belt.
【図６】本発明の他の実施例を示す断面図である。FIG. 6 is a sectional view showing another embodiment of the present invention.
２ トレッド部 ２Ａ トレッド表面 ３ サイドウォール部 ４ ビード部 ５ ビードコア ６ カーカス ７ ベルト層 ７Ａ ベルトプライ ＢＲ１ ベルト曲率半径 Ｄ タイヤ最大径 ＴＲ１ トレッド曲率半径 Ｗ タイヤ最大巾 2 tread part 2A tread surface 3 sidewall part 4 bead part 5 bead core 6 carcass 7 belt layer 7A belt ply BR1 belt curvature radius D tire maximum diameter TR1 tread curvature radius W tire maximum width
【表１】 [Table 1]
Claims (1)
０mm以上かつ１２５０mm以下、しかもトレッド部からサ
イドウォール部を通りビード部のビードコアの周りを折
返すカーカスと、トレッド部の内部かつカーカスの半径
方向外側に配されかつ１枚以上のベルトプライからなる
ベルト層とを具える空気入りラジアルタイヤであって、
タイヤ子午断面におけるトレッド部表面と、前記ベルト
層の半径方向外側のベルト層の外面とはともにタイヤ赤
道面を中心とする円弧によって形成されるとともに、ト
レッド部表面の曲率半径であるトレッド曲率半径（ＴＲ
１）はベルト層外面の曲率半径であるベルト曲率半径
（ＢＲ１）よりも大、しかも前記トレッド曲率半径（Ｔ
Ｒ１）とベルト曲率半径（ＢＲ１）との積（ＴＲ１×Ｂ
Ｒ１）は３３．７×１０4 mm2以上かつ４５．０×１０
4 mm2以下であることを特徴とする空気入りラジアルタ
イヤ。1. The sum of tire maximum width and tire maximum diameter is 75.
A belt consisting of 0 mm or more and 1250 mm or less, and a carcass that folds around the bead core of the bead part from the tread part through the sidewall part, and one or more belt plies arranged inside the tread part and radially outside the carcass. A pneumatic radial tire comprising layers,
The tread portion surface in the tire meridional section and the outer surface of the belt layer on the outer side in the radial direction of the belt layer are both formed by an arc centered on the tire equatorial plane, and the tread curvature radius that is the curvature radius of the tread portion surface ( TR
1) is larger than the belt radius of curvature (BR1) which is the radius of curvature of the outer surface of the belt layer, and the radius of curvature of the tread (T
R1) and belt radius of curvature (BR1) (TR1 × B
R1) is 33.7 × 10 4 mm 2 or more and 45.0 × 10
A pneumatic radial tire characterized by having a diameter of 4 mm 2 or less.
Priority Applications (3)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP4176269A JP2643058B2 (en) | 1991-08-26 | 1992-06-09 | Pneumatic radial tire |
| US07/917,961 US5343919A (en) | 1991-08-26 | 1992-07-24 | Pneumatic radial tire with specified belt curvature |
| AU20721/92A AU645918B2 (en) | 1991-08-26 | 1992-07-31 | A pneumatic radial tire |
Applications Claiming Priority (3)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP24039791 | 1991-08-26 | ||
| JP3-240397 | 1991-08-26 | ||
| JP4176269A JP2643058B2 (en) | 1991-08-26 | 1992-06-09 | Pneumatic radial tire |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPH05185807A true JPH05185807A (en) | 1993-07-27 |
| JP2643058B2 JP2643058B2 (en) | 1997-08-20 |
Family
ID=26497255
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP4176269A Expired - Fee Related JP2643058B2 (en) | 1991-08-26 | 1992-06-09 | Pneumatic radial tire |
Country Status (3)
| Country | Link |
|---|---|
| US (1) | US5343919A (en) |
| JP (1) | JP2643058B2 (en) |
| AU (1) | AU645918B2 (en) |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2003080906A (en) * | 2001-09-07 | 2003-03-19 | Sumitomo Rubber Ind Ltd | Radial tire for atv |
| JP2016187980A (en) * | 2015-03-30 | 2016-11-04 | 住友ゴム工業株式会社 | Pneumatic tire |
Families Citing this family (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP3358900B2 (en) * | 1993-12-16 | 2002-12-24 | 住友ゴム工業株式会社 | Pneumatic tire |
| US7090735B2 (en) | 2001-08-06 | 2006-08-15 | Bridgestone/Firestone North American Tire, Llc | Method of compensating for residual aligning torque (RAT) |
| US20120312442A1 (en) * | 2011-06-13 | 2012-12-13 | Kiyoshi Ueyoko | Reduced weight aircraft tire |
| MX2017016137A (en) * | 2015-06-30 | 2018-06-18 | Pirelli | Method and apparatus for analysing a surface of a tyre. |
| EP3915806B1 (en) * | 2019-10-16 | 2023-05-10 | Sumitomo Rubber Industries, Ltd. | Pneumatic tire |
| JP2024014499A (en) * | 2022-07-22 | 2024-02-01 | 住友ゴム工業株式会社 | tire |
Citations (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS5827122A (en) * | 1981-08-11 | 1983-02-17 | Toru Negishi | Spectacle frame for multifocuses |
Family Cites Families (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS5827122B2 (en) * | 1979-04-24 | 1983-06-07 | 横浜ゴム株式会社 | pneumatic tires |
| JPS58112805A (en) * | 1981-12-28 | 1983-07-05 | Yokohama Rubber Co Ltd:The | Radial tyre for motorcar |
| JPH02128905A (en) * | 1988-11-09 | 1990-05-17 | Sumitomo Rubber Ind Ltd | Atv tire |
-
1992
- 1992-06-09 JP JP4176269A patent/JP2643058B2/en not_active Expired - Fee Related
- 1992-07-24 US US07/917,961 patent/US5343919A/en not_active Expired - Fee Related
- 1992-07-31 AU AU20721/92A patent/AU645918B2/en not_active Ceased
Patent Citations (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS5827122A (en) * | 1981-08-11 | 1983-02-17 | Toru Negishi | Spectacle frame for multifocuses |
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2003080906A (en) * | 2001-09-07 | 2003-03-19 | Sumitomo Rubber Ind Ltd | Radial tire for atv |
| JP4705284B2 (en) * | 2001-09-07 | 2011-06-22 | 住友ゴム工業株式会社 | Radial tire for ATV |
| JP2016187980A (en) * | 2015-03-30 | 2016-11-04 | 住友ゴム工業株式会社 | Pneumatic tire |
Also Published As
| Publication number | Publication date |
|---|---|
| US5343919A (en) | 1994-09-06 |
| JP2643058B2 (en) | 1997-08-20 |
| AU645918B2 (en) | 1994-01-27 |
| AU2072192A (en) | 1993-03-04 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| EP3666556B1 (en) | Pneumatic tyre | |
| JP3100122B2 (en) | Pneumatic tire | |
| EP1010550B1 (en) | Pneumatic tyre | |
| JP3389488B2 (en) | Radial tires for heavy loads | |
| JP2544532B2 (en) | Heavy duty tires | |
| JPH03139402A (en) | Pneumatic tire | |
| JPH05185807A (en) | Pneumatic radial tire | |
| JPH07112763B2 (en) | Pneumatic radial tires | |
| JPH0648109A (en) | Pneumatic radial tire for heavy load | |
| JPH0596912A (en) | Heavy duty tire | |
| JP3254171B2 (en) | Heavy duty pneumatic tires | |
| JPH11222009A (en) | Pneumatic radial tire for heavy load | |
| JPH07186615A (en) | Pneumatic radial tire for passenger car | |
| JPH0717214A (en) | Pneumatic radial tire for heavy load | |
| JP3342912B2 (en) | Aircraft radial tires | |
| JP3425066B2 (en) | Pneumatic tire | |
| JP3021451B1 (en) | Radial tires for heavy loads | |
| JPH0648108A (en) | Pneumatic radial tire for heavy load | |
| JPH05278416A (en) | Pneumatic tire | |
| JP2000198320A (en) | Pneumatic tire | |
| JPH0958224A (en) | Pneumatic tire | |
| JP4787425B2 (en) | Pneumatic tire | |
| JP2613999B2 (en) | Pneumatic tire | |
| JPH06127211A (en) | Assembly of pneumatic radial tire | |
| JP3124851B2 (en) | Heavy duty tire |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| R250 | Receipt of annual fees |
Free format text: JAPANESE INTERMEDIATE CODE: R250 |
|
| R250 | Receipt of annual fees |
Free format text: JAPANESE INTERMEDIATE CODE: R250 |
|
| R250 | Receipt of annual fees |
Free format text: JAPANESE INTERMEDIATE CODE: R250 |
|
| R250 | Receipt of annual fees |
Free format text: JAPANESE INTERMEDIATE CODE: R250 |
|
| FPAY | Renewal fee payment (event date is renewal date of database) |
Free format text: PAYMENT UNTIL: 20090502 Year of fee payment: 12 |
|
| LAPS | Cancellation because of no payment of annual fees |